The Compound Light Microscope


Introduction

A compound light microscope is an optical instrument which magnifies objects that are too small to be seen by the naked eye.
This wiki explores the use, application and optics relating to the compound light microscope.

Using a Compound Light Microscope

How it Works:
1. Light from the projection lens illuminates a translucent species.
2. A microscope has a mirror with one curved side and one flat side. The concave side focuses the light into a path that will strike the specimen, and is typically used with indoor light. The flat side does not concentrate light, and is used mostly with outdoor light.
NOTE: Some microscopes use blue light because blue light has a shorter wavelength than yellow light, thus producing images with a
greater resolution.
3. The disc diagraphm (not shown) is an opening that controls the amount of light that is shone on the specimen.
4. Light then passes throught another system of lenses called the condenser to send up the light in parallel rays for clearer view.
5. Light passes through the objective lens, which will magnify the image.
6. Knobs on the side of the microscope allow for even, small movements of the stage to focus the image better. The coarse-adjustment
knob moves the stage up and down. The fine-focusing knob moves the stage right and left.
7. The image you see is upside down and reversed from left to right. This is because the objective lens has a very short focal length, and
the rays from the microscope cross over, giving an inverted and magnified image.

microscope_diagram

Applications:
1. The compound light microscope is used mainly in the fields of microbiology, geology, genetics, botany and forensics. Scientists
use the microscope to study minute details in small objects, in order to identify species or types of minerals.

The Optics of a Microscope

The microscope relates to the subject of optics because it utilizes a system of lens to bend light in order to magnify an image. The plane-concave mirror,
and condenser help focus the light onto the specimen. After, when the light travels through the converging lens of the objective lens and the eyepiece, the light rays diverge, creating a magnified image. This image is inverted due to the short focal length of the objective lens, and the close range between the lens and the specimen being examined. Some microscopes also use blue light, which has a short wavelength, to create high-resolutioned images.

References

1. The Biology 20 Microscope Manuel. Student Workbook. Ms. Meachem.
2. http://www.wisegeek.com/what-is-a-compound-light-microscope.htm
3. http://www.reference.com/motif/science/why-do-compound-microscopes-invert-the-images

Trecia Kilback
Physics 20
May 7, 2012